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University Medicine Project Proposal
University Medicine Project Proposal 1
Beijing Union University Graduation Project (Thesis) Project Proposal
1. Topic Tasks and purposes
1. Project tasks
This project is the design of a pulse wave extraction circuit based on a single-chip microcomputer. The design uses the digital-to-analog converter MAX1240 chip to form an AD conversion circuit plus a band-pass filter circuit and an amplification circuit to collect voltage data. Then the collected pulse signal, that is, the analog voltage value, is converted into a 12-bit digital value and input to the microcontroller. The microcontroller then The data processing is 2 bytes, the low byte is the low 8-bit data, and the low 4 bits of the high byte are the high 4 bits of the digital voltage value. After data processing, the data is sent out through the serial port.
2. Purpose of the subject
To further understand the microcontroller, master the circuit composition and design methods of the signal conditioning part, and the method of designing the data signal acquisition circuit using the microcontroller.
2. Survey data
The current pulse wave detection system has the following detection methods: photoplethysmography, liquid coupling cavity pulse sensor, piezoresistive pulse sensor and strain sensor type pulse sensor. In recent years, photoelectric detection technology has developed rapidly in clinical medical applications. This is because light can avoid strong electromagnetic interference, has high insulation, and can non-invasively detect various patient symptom information. Using photoelectric method to extract fingertip pulse light information is currently the best method.
Digital design method of pulse wave detection system: Extracting physiological and pathological information of the human body from pulse waves as the basis for clinical diagnosis and treatment has always been valued by the Chinese and foreign medical circles. Almost all ethnic groups in the world have used "pulse feeling" as a means of diagnosing diseases. The comprehensive information presented by the pulse wave in terms of shape (waveform), intensity (amplitude), rate (wave speed) and rhythm (period) reflects to a large extent many physiological and pathological blood flow characteristics in the human cardiovascular system. , so it has high medical value and application prospects for pulse wave collection and processing. However, the biological signals of the human body are mostly low-frequency weak signals under a strong noise background, and the pulse wave signal is a weak low-frequency non-electrophysiological signal, which must be amplified and post-filtered to meet the collection requirements.
The current fingertip pulse detection systems use analog technology to complete filtering, amplification and integer processing, and then undergo analog-to-digital conversion and further processing. This method not only increases the complexity of the hardware, increases power consumption and volume, but more importantly, increases system unreliability and instability. With the rapid development of electronic measurement technology, modern electronic measurement instruments are developing in the direction of digitization and automation at an extremely fast speed.
About the waveform of pulse wave
Pulse wave is formed when the heart’s pulsation (vibration) propagates to the periphery along the arteries and blood flow, so its propagation speed depends on the propagation medium. Physical and geometric properties - the elasticity of arteries, the size of the lumen, the density and viscosity of blood, etc., are especially closely related to the elasticity, caliber and thickness of the arterial wall. Experiments have found that the greater the elasticity of arterial blood vessels (that is, the greater the compliance), the smaller the propagation speed of pulse waves; the smaller the diameter of arteries, the greater the speed. Therefore, usually along the aorta to large arteries and then to smaller arteries, the pulse wave propagation speed becomes larger and larger.
The landmark characteristics of the pulse wave periodogram are closely related to their corresponding physiological factors, which have an important impact on the correct extraction of cardiovascular function parameter index information.
As shown in Figure 1, b the starting point of the single wave (the opening point of the aortic valve), c the main wave peak (the highest pressure point of the aorta), d the peak of the pre-diploid wave (the first inflection point after the pressure at point c drops, which is the left Caused by the elastic vibration of the aorta caused by the impact of ventricular ejection), the starting point of e diastole, the trough of f diplex wave (the marking point where the atrioventricular valve begins to open and the left ventricle begins to fill), the peak of g diplex wave (posterior artery at point f) The pressure continues to rise to a peak). Ps is the systolic blood pressure, Pd is the diastolic blood pressure, Pm1 is the average systolic pressure, and Pm2 is the average diastolic pressure.
Figure 1 Specific characteristics of pulse wave
Main reference materials
[1]/link?url=7Z9o5jW68XKWE0NaLZ1GKdLKrcaFSWGIjWKe988_YWveCz-t_X6nnoTTofY5ouYUOcdbJLUwI-sk9gs0OnNueXAOoYqcQQlUlgL mALAHkRi (related to others' microcontroller-based Design scheme of pulse wave extraction circuit)
[2]/view/9b9e716f1eb91a37f1115cda.html (Characteristic monitoring of pulse wave)
[3] National College Student Electronic Design Competition Organizing Committee .Selected Works from the National Undergraduate Electronic Design Competition Award-winning Works (2003). Beijing: Beijing Institute of Technology Press, 2003, First Edition
[4] Zhou Runjing. Single-chip microcomputer circuit design, analysis and production. Beijing: Mechanical Industrial Press, 1st Edition on August 1, 2010
[5] Zhang Yongge/Huang Qinghua. Microcontroller Development Technology and Practical Training. Electronic Industry Press. 2006, First Edition
[6] Lingyang Technology. "Lingyang 16-bit MCU Development Example". Beijing University of Aeronautics and Astronautics Press
[7]: SGS-Thomson Microelectronics Application Note. "Applications of Mololithic Bridge divers" [M]》
[8]： Nordic VLSI ASA PRODUCT SPECIFICATION.《433MHz Single Chip RF Transceiver Nrf401[M]》. February. 2002
[9]Tan Haoqiang. C program Design. Beijing: Tsinghua University Press, 2001.
3. Preliminary design method and implementation plan
Figure 2 Overall system block diagram
The overall process is: The pulse wave is first extracted by the HK2000B piezoelectric pulse sensor of the pulse wave signal extraction module, and then enters the pulse signal conditioning module for filtering and amplification, and then sends the conditioned digital wave to the A/D conversion module, which is converted into an analog waveform by MAX1240. It is transmitted to the microcontroller for processing, and finally the wave completed by the microcontroller is transmitted to the PC by the serial communication module.
1. Pulse signal extraction module
Currently, the most commonly used method of taking pulses in clinical TCM is the cunkou method, where the arterial path is relatively fixed, the anatomical position is shallow, and adjacent The tissue is relatively clear, so it becomes a favorable location for pulse diagnosis. This project uses the HK2000B piezoelectric pulse sensor, which has small precision and high sensitivity, and its output is an analog signal.
Attached are the factory technical specifications;
(1) Power supply voltage: DC5~6V;
(2) Pressure range: -50~300mmHg;
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(3) Sensitivity: 2000?V/mmHg;
(4) Sensitivity temperature coefficient: 0.0001/?C;
(5) Accuracy: 1.5;
(6) Repeatability: 0.5:
(7) Hysteresis: 0.5;
(8) Overload: 100 times.
2. Pulse signal conditioning module
(1) Filter circuit
The main frequency band range of conventional pulse signals is 0.1 to 40Hz. In order to prevent various noises from being mixed into the pulse signal in an interference environment, a band-pass filter circuit with a passband frequency of 0.1 to 40Hz is designed in this system to separate the useful components of the pulse signal from the collected signal. The bandpass filter of this topic will be implemented by using a 44Hz second-order low-pass filter cascaded with a 0.1Hz second-order high-pass filter.
(2) Amplification circuit
Use a transistor and a resistor to form an amplification circuit. The reference multiple is 8 to 10 times. The specific amplification factor can be tested during simulation.
3.A/D conversion module
MAX1240 is called an analog-to-digital converter; referred to as "analog-to-digital converter". A device that converts analog quantities into digital quantities. In the computer control system, various detection devices must be used to use continuously changing voltage or current as analog quantities to provide relevant parameters (such as speed, pressure, temperature, etc.) of the controlled object at any time for control. The input of the computer must be digital, so an analog-to-digital converter is needed to achieve control purposes.
Main parameters
1.2.7V~3.6V single power supply.
2. The resolution is 12 bits.
3. The maximum sampling rate is 73K times/second.
4. Low power consumption, 37Mw (73Ksps), 5Uw (standby operation).
5. Internal sampling/holding circuit is provided.
6. Conversion clock is provided internally.
Pin 3 (SHDN) is the control terminal. Its value is 0 for standby mode and 1 for normal working mode. It can also be left floating. At this time, the internal power supply is invalid. It can be connected to pin 3 ( Vref) external reference power supply.
Figure 3 MAX1240 internal pin diagram
4. Microcontroller module
This topic uses AT89S52 microcontroller, because the MCS-51 series microcontroller is cheap and versatile. Well, the market application is mature. Among them, AT89S52 has low power consumption and high performance, which is convenient for testing and debugging of various programs. It is very suitable for this design, so it was selected as the subject microcontroller.
5. Serial communication module
Serial communication can be divided into two forms: asynchronous transmission and synchronous transmission. The characteristic of asynchronous transmission is that the data is transmitted discontinuously on the line, but the communication parties The transmitted character format and baud rate must be agreed upon in advance. The speed of synchronous transmission is higher than that of asynchronous transmission, but the hardware equipment is more complex and the phase consistency requirements of the synchronous clock signal are strict.
The following are several consistent concepts and standards for serial communication:
1) Transmission rate: that is, the baud rate, generally ranging from 110 to 9600.
2) RS232-C: EIA level and TTL level conversion requires the level conversion chip MAX3232.
3) 3.0~5.5V power supply.
4) 300?A low supply current.
5) Only an external 0.1?F capacitor is required.
6. Power module
The pulse conditioning circuit requires -5, V 5V analog power supply, the microcontroller requires 5V digital power supply, the A/D converter and MAX3232 require 3.3V digital power supply, the digital The power supply needs to be separated from the analog power supply.
IV. Expected results
The circuit for pulse wave extraction has been completed and simulated successfully. The waveform can be tested and recorded. If it goes smoothly and conditions permit, the hardware operation will be performed. Finally, the graduation thesis will be completed. of preparation.
5. Progress plan
The first, second, third and fourth weeks: research data.
Weeks 5, 6, and 7: Analyze and study the found information.
Weeks 8, 9, 10, and 11: Start circuit design and simulation.
Twelve and thirteen weeks: Debugging the circuit and making final modifications.
Weeks 14 and 15: Writing a graduation thesis.
Week 16: Complete the graduation project, review by the teacher, and complete the graduation defense.
University Medical Thesis Proposal 2
Graduation is approaching. Have you finished writing your thesis? The following is a sample medical proposal report. I hope you will gain something!
Title: Design of intelligent switch for patients lying on the ground to call for help
(1) Topic selection background
With the rapid changes in science and technology and the rapid improvement of living standards, people have higher requirements for physical health protection. Getting higher and higher. When a patient suffers from a sudden illness such as heart disease, cerebral hemorrhage, hypoglycemia, or epilepsy, the patient's life safety will largely depend on whether the patient can receive effective assistance in the shortest possible time. This naturally promotes the development of first aid services and the popularization of common first aid knowledge. However, in China, the entire first aid system is still in its infancy, and there are many hidden dangers that may affect the efficiency of first aid after a patient suddenly becomes ill. For example, what should you do if a patient with a heart attack suddenly falls ill and collapses while walking on the roadside? Make a phone call? What if there is no public telephone number nearby? Find someone for help? Once it is handled incorrectly by non-professionals, it is likely to delay treatment. Self-defeating. Take a taxi to the hospital? Data shows that brain cells begin to die 5-10 minutes after the patient's heart stops. In other words: In this case, professional emergency personnel must arrive as soon as possible to ensure the patient's life safety. Thinking from this perspective, I came up with this idea: Can a device be designed to simplify the process from a patient falling due to a sudden onset to the doctor arriving for treatment as quickly as possible?
I am at the patent office. After checking the relevant information, I found that there is currently no such product design in China. A similar creative design is to set two metal contacts in a bottle, and fill the bottle with some mercury. When a person stands, the mercury concentrates at a contact point and the circuit is broken. When a person falls to the ground, the tilt of the bottle causes the mercury to contact two contacts at the same time, the circuit is triggered, and the alarm built into the bottle sounds an alarm to signal for help. This design is obviously very crude.
(1) It only determines whether to call the police based on the angle of body tilt, rather than based on the true physiological condition, which will inevitably lead to a high false alarm rate.
(2) It only attracts others’ attention in the shortest time, but does not simplify the entire process, so it will not have a substantial impact on improving rescue efficiency.
Combining my own ideas and the shortcomings of existing facilities, I hope to make a "first aid system after falling to the ground": when the patient falls to the ground, use a monitoring device to sense the patient's blood pressure, pulse, etc. Physiological conditions and conduct numerical analysis. Once it is determined that the patient has become ill, a radio signal is sent to the nearest first aid station. The first aid station locates the patient's location through GPS and dispatches emergency personnel as quickly as possible.
However, after more than two months of discussion, there was almost no progress, and I almost gave up.
However, with the constant encouragement and inspiration from the teacher, one day, inspiration fortunately came to my brain? Sound and light help, wired and wireless telephone alarms are all mature technologies. The key is that none of them can judge whether the patient fell due to other reasons or not. Smart switch device for sudden onset of illness and fall.
Once this design can be realized, it will have great practical and social value. First of all, it gives patients the greatest protection in the most critical aspect of first aid, greatly reducing the risk of sudden diseases; secondly, it will bring about new concepts and new operating models in the first aid industry, and will also Promote the popularization and promotion of related products (such as GPS); in addition, it can enable many middle-aged and elderly people suffering from sudden diseases to face life with a relaxed and optimistic mood, participate in more social activities, and the resulting social The effect will be considerable.